Stose.] 
370 
I May i6, 
In June, 1893, I obtained a nearly com})lete s})eciinen on a slab 
of the Water Lime strata from Buflfalo, N. Y., wliich I will 
describe in detail. It is flattened on the rock, showing the side 
of the body. The carapace is detached and reversed in position. 
The carapace is somewhat rhomboidal in outline, as can be 
"^. 
observed in the figure. Length between the extremities of the 
hinge line 4^ inches. The maximum width at right angles to 
this, which is about at tlie middle, is 2J inches. The posterior 
margin is slightly concave, curving sharply forward at the base. 
The anterior margin is nearly straight, and curves gently back- 
ward at the base. The dorsal margin is slightly convex, bending 
downward more sharply at both ends. The acuminate point in 
front, mentioned by Professor Hall, is not visible. The ventral 
margin is about at right angles with the posterior margin. The 
anterior and ventral sides are marked by a narrow raised border. 
No ocular spot is visible. The surface is marked by fine 
curving lines, not shown in the sketch, running along the anterior 
margin and turning back parallel with the lower outline, the 
u])per ones ending abruptly in the hinge line, the lower ones in 
the posterior margin. The majority show only under the lens, 
those along the anterior and basal margins showing more distinctly. 
Three quarters of an inch from the front end of the hinge, two 
slender, tapering apjiendages ])roject upward and forward. These 
may l)e spines on the cara])ace, but more probably were antennae 
